Submitted to: Commonwealth Agricultural Bureaux International
Publication Type: Review Article
Publication Acceptance Date: October 5, 2010
Publication Date: November 30, 2010
Citation: Qureshi, N. 2010. Agricultural residues and energy crops as potentially economical and novel substrates for microbial production of butanol (a biofuel). Commonwealth Agricultural Bureaux International. 5(59):1-8.
This review describes production of acetone butanol ethanol (ABE) from a variety of agricultural residues and energy crops employing biochemical or fermentation processes. A number of organisms are available for this bioconversion including Clostridium beijerinckii P260, C. beijerinckii BA101, C. acetobutylicum, and C. saccharobutylicum P262. Some of these strains (P260 and P262) were used in an industrial setting in South Africa. One of the major limitations of these cultures is that none of them produce greater than 30 g/L total ABE unless integrated with simultaneous product recovery to reduce the toxicity of accumulated products. These cultures can utilize both hexose and pentose sugars derived from lignocellulosic hydrolysates such as corn fiber, wheat straw (one of the novel substrates), barley straw, corn stover, and switchgrass. Substrates such as Jerusalem artichoke, corn, rye, millet, molasses, potato, soy molasses, and agricultural wastes can also be used by the above cultures. Additional carbohydrates that can be used include dextrins, fructose, sucrose, and lactose. It is recommended that cultures that can produce greater amounts of ABE per L culture broth be developed. In order to economize the process of butanol production by fermentation, process technologies have been developed that integrate lignocellulosic biomass hydrolysis, fermentation, and simultaneous product recovery. It should be noted that in a continuous process where product was recovered simultaneously, 461.3 g/L ABE was produced from 1125 g sugar in a 1 L culture volume.